curry.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/
 
#pragma once
 
#include <tuple>
#include <type_traits>
#include <utility>
 
namespace LC
{
namespace Util
{
    template<typename F, typename... PrevArgs>
    class CurryImpl
    {
        F m_f;
 
        std::tuple<PrevArgs...> m_prevArgs;
    public:
        template<typename CF, typename CT>
        CurryImpl (CF&& f, CT&& prev)
        : m_f { std::forward<CF> (f) }
        , m_prevArgs { std::forward<CT> (prev) }
        {
        }
 
        template<typename T>
        auto operator() (T&& arg) const &
        {
            return run (*this, std::forward<T> (arg));
        }
 
        template<typename T>
        auto operator() (T&& arg) &
        {
            return run (std::as_const (*this), std::forward<T> (arg));
        }
 
        template<typename T>
        auto operator() (T&& arg) &&
        {
            return run (std::move (*this), std::forward<T> (arg));
        }
    private:
        template<typename This, typename T>
        static auto run (This&& refThis, T&& arg)
        {
            if constexpr (std::is_invocable_v<F, PrevArgs..., T>)
            {
                auto wrapper = [&refThis, &arg] (auto&&... args)
                {
                    return std::invoke (std::move (refThis.m_f), std::forward<decltype (args)> (args)..., std::forward<T> (arg));
                };
                return std::apply (std::move (wrapper), std::move (refThis.m_prevArgs));
            }
            else
                return CurryImpl<F, PrevArgs..., T>
                {
                    std::move (refThis.m_f),
                    std::tuple_cat (std::move (refThis.m_prevArgs), std::forward_as_tuple (std::forward<T> (arg)))
                };
        }
    };
 
    template<typename F, typename... Args>
    CurryImpl<std::decay_t<F>, Args...> Curry (F&& f, Args&&... args)
    {
        return { std::forward<F> (f), std::forward_as_tuple (std::forward<Args> (args)...) };
    }
}
}